From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Dec 17 2003 - 01:39:59 GMT-3
Alec,
Yes, pass-thru is required when peering direct over HDLC or SDLC. See
the following output:
R1(config)#dlsw remote-peer 0 interface serial 0/0
%For direct encapsulation, must specify pass-thru
The keyword is optional for Frame Relay because it can support
reliable transport by incorporating an additional LLC2 header after the
Frame Relay header.
R1(config)#dlsw remote-peer 0 frame-relay interface serial 0/0 102
The above statement illustrates dlsw over frame relay *with* reliable
transport (local ack), and implies the following interface level
configuration:
R1(config)#int s0/0
R1(config-if)#frame-relay map llc2 102 broadcast
R1(config)#dlsw remote-peer 0 frame-relay interface serial 0/0 102 pass-thru
The above statement illustrates dlsw over frame relay *without*
reliable transport (no local ack), and implies the following interface level
configuration:
R1(config)#int s0/0
R1(config-if)#frame-relay map dlsw 102 broadcast
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 708-362-1418 (Outside the US and Canada)
_____
From: Pun, Alec CL [mailto:Alec.CL.Pun@pccw.com]
Sent: Tuesday, December 16, 2003 7:37 PM
To: Brian McGahan; ccielab@groupstudy.com
Subject: RE: DLSW pass-through
Brian,
Thanks. Does that mean when configuring direct encapsulation over HDLC, the
pass-through option must be specified ? For FR, this parameter is optional.
For TCP, it has already been enabled and you can not change it by default!
rgds,
alec
-----Original Message-----
From: Brian McGahan [mailto:bmcgahan@internetworkexpert.com]
Sent: Wednesday, December 17, 2003 6:40 AM
To: Pun, Alec CL; ccielab@groupstudy.com
Subject: RE: DLSW pass-through
Alec,
Frame Relay, HDLC, and SDLC do not provide reliable transport. In
the case that a packet is lost when sent across these encapsulations it is
the responsibility of the host to retransmit. For this reason the router
cannot guarantee to the host that the packet has gotten through (local
acknowledgement).
Local ack is only supported with TCP (reliable by nature) and Frame
Relay with an additional LLC2 header, which provides error checking and
retransmission.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 708-362-1418 (Outside the US and Canada)
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Pun, Alec CL
> Sent: Tuesday, December 16, 2003 10:34 AM
> To: ccielab@groupstudy.com
> Subject: DLSW pass-through
>
> From Doccd, the examples for DLSW direct and frame-relay encapsulation
> always use the pass-thru parameters. Why they are used to disable local
> acknolwedgement ? Isn't local acknolwedgement is more suitable as they
> offer
> more reliability ?
>
> [extract]
> dlsw remote-peer 0 frame-relay interface serial 1 40 pass-thru
> dlsw remote-peer 0 interface serial 1 pass-thru
>
> rgds,
> alec
>
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